Have you ever needed to type something on your iPhone in all capital letters, but every time you tapped the shift button you type one letter that’s capitalized but all the letters you type after that are lowercase letters? That can get pretty frustrating. However, there is a solution. Your iPhone has a Caps Lock feature, which works just like the Caps Lock on your computer. You can simply turn Caps Lock on and have all the letters you type be capitalized.
This quick tutorial will teach you how to enable the Caps Lock feature on your iPhone and then how to turn Caps Lock on and off when typing on your iPhone keyboard.
Let’s get started.
We will begin by making sure that the Caps Lock feature is enabled. To do this tap on your Settings app.
Next, tap on General.
Scroll down and tap on Keyboard.
The fourth item down will say Enable Caps Lock. Make sure the toggle directly to the right is switched to On.
Now that Caps Lock is enabled, let’s try turning Caps Lock on in a text message. (Note: Caps Lock will work most anywhere you can type with your iPhone keyboard. The feature is not just limited to text messages.)
When you open your Messages app (or any other app where you can type on your iPhone keyboard), notice that the shift button on the keyboard is glowing white. This means that the next letter that you type will be capitalized. However, after you type that first letter, the next letters you type will be lower case letters.
To turn Caps Lock on, so that all that letters you type are capital letters, quickly tap twice on the shift button. The shift button will turn blue to let you know that Caps Lock is now turned on.
To turn Caps Lock off, simply tap once on the shift button. The button will turn gray and Caps Lock will be turned off.
That’s all there is to it!
SimpleiPhone 
I am a 73 year old and a NEW user to the iphone 5 or I should say any iphone as I had an LG phone and it is quite different. The above instructions were very simple and easy to understand as it gave both written and visual instructions in “step” order. Thank you so much.
So simple once you know how!